TY - CHAP A1 - Kallweit, Stephan A1 - Gottschalk, Michael A1 - Walenta, Robert T1 - ROS based safety concept for collaborative robots in industrial applications T2 - Advances in robot design and intelligent control : proceedings of the 24th International Conference on Robotics in Alpe-Adria-Danube Region (RAAD). (Advances in intelligent systems and computing ; 371) N2 - The production and assembly of customized products increases the demand for flexible automation systems. One approach is to remove the safety fences that separate human and industrial robot to combine their skills. This collaboration possesses a certain risk for the human co-worker, leading to numerous safety concepts to protect him. The human needs to be monitored and tracked by a safety system using different sensors. The proposed system consists of a RGBD camera for surveillance of the common working area, an array of optical distance sensors to compensate shadowing effects of the RGBD camera and a laser range finder to detect the co-worker when approaching the work cell. The software for collision detection, path planning, robot control and predicting the behaviour of the co-worker is based on the Robot Operating System (ROS). A first prototype of the work cell shows that with advanced algorithms from the field of mobile robotics a very flexible safety concept can be realized: the robot not simply stops its movement when detecting a collision, but plans and executes an alternative path around the obstacle. KW - Collaborative robot KW - Human-Robot interaction KW - Safety concept KW - Workspace monitoring KW - Path planning Y1 - 2016 SN - 978-3-319-21289-0 (Print) ; 978-3-319-21290-6 (E-Book) U6 - http://dx.doi.org/10.1007/978-3-319-21290-6_3 SP - 27 EP - 35 PB - Springer CY - Cham ER - TY - JOUR A1 - Fateri, Miranda A1 - Gebhardt, Andreas T1 - Additive manufactured mechanical disentanglement lock JF - RTejournal - Forum für Rapid Technologie Y1 - 2015 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0009-2-42147 SN - 1614-0923 VL - 12 PB - Fachhochschule Aachen CY - Aachen ER - TY - CHAP A1 - Großmann, Agnes A1 - Gabrielli, Roland Antonius A1 - Herdrich, Georg A1 - Fasoulas, Stefanos A1 - Schnauffer, Peter A1 - Middendorf, Peter A1 - Fateri, Miranda A1 - Gebhardt, Andreas T1 - Overview of the MultiRob 3D Lunar Industrial Development Project T2 - Conference Contribution for the 30th ISTS, Kobe, Japan, 04.07.-10.07.2015 Y1 - 2015 ER - TY - CHAP A1 - Ferrein, Alexander A1 - Kallweit, Stephan A1 - Scholl, Ingrid A1 - Reichert, Walter T1 - Learning to Program Mobile Robots in the ROS Summer School Series T2 - Proceedings 6th International Conference on Robotics in Education (RiE 15) N2 - The main objective of our ROS Summer School series is to introduce MA level students to program mobile robots with the Robot Operating System (ROS). ROS is a robot middleware that is used my many research institutions world-wide. Therefore, many state-of-the-art algorithms of mobile robotics are available in ROS and can be deployed very easily. As a basic robot platform we deploy a 1/10 RC cart that is wquipped with an Arduino micro-controller to control the servo motors, and an embedded PC that runs ROS. In two weeks, participants get to learn the basics of mobile robotics hands-on. We describe our teaching concepts and our curriculum and report on the learning success of our students. Y1 - 2015 ER - TY - CHAP A1 - Gregorio, Fabrizio de A1 - Fatigati, Giovanni A1 - Kallweit, Stephan T1 - Tiltrotor airframe flow field characterization by SPIV T2 - 11th International Symposium on Partivle Image Velocimetry - PIV15 , Santa Barbara, California, Sept 14-16, 2015 Y1 - 2015 ER - TY - CHAP A1 - Alhwarin, Faraj A1 - Ferrein, Alexander A1 - Gebhardt, Andreas A1 - Kallweit, Stephan A1 - Scholl, Ingrid A1 - Tedjasukmana, Osmond Sanjaya T1 - Improving additive manufacturing by image processing and robotic milling T2 - 2015 IEEE International Conference on Automation Science and Engineering (CASE), Aug 24-28, 2015 Gothenburg, Sweden Y1 - 2015 U6 - http://dx.doi.org/10.1109/CoASE.2015.7294217 SP - 924 EP - 929 ER - TY - JOUR A1 - Kessler, Julia A1 - Balc, Nicolae A1 - Gebhardt, Andreas A1 - Abbas, Karim T1 - Basic Research on Lattice Structures Focused on the Tensile Strength JF - Applied Mechanics and Materials Y1 - 2015 U6 - http://dx.doi.org/10.4028/www.scientific.net/AMM.808.193 SN - 1662-7482 N1 - MTeM ; October 14-16, 2015, Cluj-Napoca, Romania VL - Vol. 808 SP - 193 EP - 198 PB - Trans Tech Publications CY - Bäch ER - TY - CHAP A1 - Fateri, Miranda A1 - Gebhardt, Andreas A1 - Gabrielli, Roland Antonius A1 - Herdrich, Georg A1 - Fasoulas, Stefanos A1 - Großmann, Agnes A1 - Schnauffer, Peter A1 - Middendorf, Peter T1 - Additive Manufacturing of Lunar Regolith for Extra-terrestrial Industry Plant T2 - International Symposium on Space Technology and Science (ICTS). July 2015, Kobe, Japan Y1 - 2015 ER - TY - CHAP A1 - Gabrielli, Roland Antonius A1 - Mathies, Johannes A1 - Großmann, Agnes A1 - Herdrich, Georg A1 - Fasoulas, Stefanos A1 - Middendorf, Peter A1 - Fateri, Miranda A1 - Gebhardt, Andreas T1 - Space Propulsion Considerations for a Lunar Take Off Industry Based on Regolith T2 - International Symposium on Space Technology and Science (ISTS). July 2015, Kobe, Japan Y1 - 2015 ER - TY - CHAP A1 - Fateri, Miranda A1 - Gebhardt, Andreas A1 - Renftle, Georg T1 - Additive Manufacturing of Drainage Segments for Cooling System of Crucibles Melting Furnaces T2 - International Conference and Expo on Advanced Ceramics and Composites, (ICACC). January 2015, Florida, USA N2 - The cooling process in induction based crucible melting furnaces for Industrial applications is one of the important and challenging factors in production and safety engineering. Accordingly, proper implementation of the cooling system of the furnace using optimum cooling guides and fail-safe features are critical in order to improve the safety of the process. Regarding this, manufacturing of porous material with high electrical isolation for the drainage segments of the cooling channels is examined in this study. Consequently, various geometries with different porosities using glass and ceramic powder are fabricated using Selective Laser Sintering (SLS) process. The manufactured parts are examined in a prototype furnace testing and the feasibility of the SLS manufacturing of parts for this application is discussed. Y1 - 2015 ER - TY - CHAP A1 - Nakagawa, Masaki A1 - Michaux, Frank A1 - Kallweit, Stephan A1 - Maeda, Kazuhiro T1 - Unsteady flow measurements in the wake behind a wind-tunnel car model by using high-speed planar PIV T2 - 11TH International Symposium on Particle Image Velocimetry – PIV15 Santa Barbara, California, September 14-16, 2015 N2 - This study investigates unsteady characteristics of the wake behind a 28%-scale car model in a wind tunnel using highspeed planar particle image velocimetry (PIV). The car model is based on a hatchback passenger car that is known to have relatively high fluctuations in its aerodynamic loads. This study primarily focuses on the lateral motion of the flow on the horizontal plane to determine the effect of the flow motion on the straight-line stability and the initial steering response of the actual car on a track. This paper first compares the flow fields in the wake behind the above mentioned model obtained using conventional and high-speed planar PIV, with sampling frequencies of 8 Hz and 1 kHz, respectively. Large asymmetrically coherent flow structures, which fluctuate at frequencies below 2 Hz, are observed in the results of highspeed PIV measurements, whereas conventional PIV is unable to capture these features of the flow owing to aliasing. This flow pattern with a laterally swaying motion is represented by opposite signs of cross-correlation coefficients of streamwise velocity fluctuations for the two sides of the car model. Effects of two aerodynamic devices that are known to reduce the fluctuation levels of the aerodynamic loads are then extensively investigated. The correlation analyses reveal that these devices indeed reduce the fluctuation levels of the flow and the correlation values around the rear combination-lamp, but it is found that the effects of these devices are different around the c-pillar. Y1 - 2015 ER - TY - CHAP A1 - Kilic, S. A. A1 - Raatschen, Hans-Jürgen A1 - Astaneh-Asl, A. A1 - Apaydin, N. M. T1 - Finite element modeling of the Fatih Sultan Mehmet Suspension Bridge T2 - Multi-Span Large Bridges - Proceedings of the International Conference on Multi-Span Large Bridges Y1 - 2015 SN - 9781138027572 SP - 1169 EP - 1173 PB - CRC Press CY - Leiden ER - TY - CHAP A1 - Wollert, Jörg T1 - Wireless systems for machinery safety : Requirements and solutions for wireless real time systems T2 - 16th International Conference on Research and Education in Mechatronics (REM), 2015 Y1 - 2015 SN - 978-3-945728-01-7 U6 - http://dx.doi.org/10.1109/REM.2015.7380377 SP - 88 EP - 91 ER - TY - CHAP A1 - Nakagawa, Masaki A1 - Kallweit, Stephan A1 - Michaux, Frank A1 - Hojo, Teppei T1 - Typical Velocity Fields and Vortical Structures around a Formula One Car, based on Experimental Investigations using Particle Image Velocimetry T2 - SAE International Journal of Passenger Cars - Mechanical Systems Y1 - 2016 U6 - http://dx.doi.org/10.4271/2016-01-1611 SN - 1946-4002 ER - TY - BOOK A1 - Gebhardt, Andreas A1 - Hötter, Jan-Steffen T1 - Additive manufacturing : 3D printing for prototyping and manufacturing Y1 - 2016 SN - 978-1-56990-582-1 ; 978-1-56990-583-8 PB - Hanser Publishers CY - Munich ER - TY - JOUR A1 - Koster, Arie A1 - Scheidweiler, Robert A1 - Tieves, Martin T1 - A flow based pruning scheme for enumerative equitable coloring algorithms JF - A flow based pruning scheme for enumerative equitable coloring algorithms N2 - An equitable graph coloring is a proper vertex coloring of a graph G where the sizes of the color classes differ by at most one. The equitable chromatic number is the smallest number k such that G admits such equitable k-coloring. We focus on enumerative algorithms for the computation of the equitable coloring number and propose a general scheme to derive pruning rules for them: We show how the extendability of a partial coloring into an equitable coloring can be modeled via network flows. Thus, we obtain pruning rules which can be checked via flow algorithms. Computational experiments show that the search tree of enumerative algorithms can be significantly reduced in size by these rules and, in most instances, such naive approach even yields a faster algorithm. Moreover, the stability, i.e., the number of solved instances within a given time limit, is greatly improved. Since the execution of flow algorithms at each node of a search tree is time consuming, we derive arithmetic pruning rules (generalized Hall-conditions) from the network model. Adding these rules to an enumerative algorithm yields an even larger runtime improvement. Y1 - 2016 U6 - http://dx.doi.org/10.48550/arXiv.1607.08754 N1 - Lehrstuhl II für Mathematik, RWTH Aachen University SP - 1 EP - 30 ER - TY - JOUR A1 - Beckenbach, Isabel A1 - Scheidweiler, Robert T1 - Perfect ƒ-Matchings and ƒ-Factors in Hypergraphs - A Combinatorial Approach JF - Discrete Mathematics N2 - We prove characterizations of the existence of perfect ƒ-matchings in uniform mengerian and perfect hypergraphs. Moreover, we investigate the ƒ-factor problem in balanced hypergraphs. For uniform balanced hypergraphs we prove two existence theorems with purely combinatorial arguments, whereas for non-uniform balanced hypergraphs we show that the ƒ-factor problem is NP-hard. Y1 - 2016 U6 - http://dx.doi.org/10.1016/j.disc.2017.05.005 SN - 2192-7782 N1 - Als Volltext auch bei ZIB (Zuse Institute Berlin) VL - 240 IS - 10 SP - 2499 EP - 2506 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Scheidweiler, Robert A1 - Triesch, Eberhard T1 - A note on the duality between matchings and vertex covers in balanced hypergraphs JF - Journal of Combinatorial Optimization N2 - We present a new Min-Max theorem for an optimization problem closely connected to matchings and vertex covers in balanced hypergraphs. The result generalizes Kőnig’s Theorem (Berge and Las Vergnas in Ann N Y Acad Sci 175:32–40, 1970; Fulkerson et al. in Math Progr Study 1:120–132, 1974) and Hall’s Theorem (Conforti et al. in Combinatorica 16:325–329, 1996) for balanced hypergraphs. KW - Hall’s Theorem KW - Koenig’s Theorem KW - Duality KW - Balanced hypergraph KW - Hypergraph KW - Vertex cover KW - Matching Y1 - 2016 U6 - http://dx.doi.org/10.1007/s10878-015-9887-5 SN - 1573-2886 N1 - Lehrstuhl II für Mathematik RWTH Aachen VL - 32 IS - 2 SP - 639 EP - 644 PB - Springer CY - Berlin ER - TY - JOUR A1 - Kilic, S. A. A1 - Raatschen, Hans-Jürgen A1 - Körfgen, B. A1 - Apaydin, N. M. A1 - Astaneh-Asl, A. T1 - FE Model of the Fatih Sultan Mehmet Suspension Bridge Using Thin Shell Finite Elements JF - Arabian Journal for Science and Engineering N2 - This paper presents the results of an eigenvalue analysis of the Fatih Sultan Mehmet Bridge. A high-resolution finite element model was created directly from the available design documents. All physical properties of the structural components were included in detail, so no calibration to the measured data was necessary. The deck and towers were modeled with shell elements. A nonlinear static analysis was performed before the eigenvalue calculation. The calculated natural frequencies and corresponding mode shapes showed good agreement with the available measured ambient vibration data. The calculation of the effective modal mass showed that nine modes had single contributions higher than 5 % of the total mass. They were in a frequency range up to 1.2 Hz. The comparison of the results for the torsional modes especially demonstrated the advantage of using thin shell finite elements over the beam modeling approach. KW - Suspension bridge KW - 3D nonlinear finite element model KW - Thin shell finite elements KW - Natural frequency KW - Effective modal mass Y1 - 2017 U6 - http://dx.doi.org/10.1007/s13369-016-2316-y SN - 2191-4281 VL - 42 IS - 3 SP - 1103 EP - 1116 PB - Springer Nature ER - TY - JOUR A1 - Rieper, Harald A1 - Gebhardt, Andreas A1 - Stucker, Brent T1 - Selective Laser Melting of the Eutectic Silver-Copper Alloy Ag 28 wt % Cu JF - RTejournal - Forum für Rapid Technologie N2 - The aim of this work was to perform a detailed investigation of the use of Selective Laser Melting (SLM) technology to process eutectic silver-copper alloy Ag 28 wt. % Cu (also called AgCu28). The processing occurred with a Realizer SLM 50 desktop machine. The powder analysis (SEM-topography, EDX, particle distribution) was reported as well as the absorption rates for the near-infrared (NIR) spectrum. Microscope imaging showed the surface topography of the manufactured parts. Furthermore, microsections were conducted for the analysis of porosity. The Design of Experiments approach used the response surface method in order to model the statistical relationship between laser power, spot distance and pulse time. KW - SLM KW - Response Surface Method KW - Porositat KW - Eutectic Silver Copper alloy KW - Additive Manufacturing Y1 - 2016 U6 - http://nbn-resolving.de/urn/resolver.pl?nbn:de:0009-2-44141 SN - 1614-0923 VL - 13 ER -